In general backup users conFigure save sets in a management interface by specifying the volume to be backed up (e.g., “C:\”, or “/user”, etc.). In normal scenarios the entire save set (e.g., a volume) would be backed up. However, sometimes backing up the entire save set may not be desirable if the save set contains some trivial data. Vendors typically provide solutions to exclude the trivial data from the backup image file. For example, the user may be able to exclude unnecessary files (e.g., .jpeg image files, or .inf setup information files, etc.) from the backup image file of a volume. The technique and functionality of excluding or removing files from a backup image file may be referred to as exclude list. Generally, three categories of files may be excluded with an exclude list: 1) files belonging to a specific VSS (Volume Shadow Copy Service) writer (e.g., a Microsoft Exchange server writer or a SQL “Structured Query Language” database server writer, etc.), 2) vendor pre-defined files (e.g., a pagefile such as “pagefile.sys”), and 3) user-specified files.
Conventionally, in a block-based backup system, excluding files may involve snapshotting the volume, determining blocks corresponding to the files to be excluded, and deleting these blocks from the snapshot. However, not all volume managers may provide snapshotting capabilities or capabilities to write to the snapshots. Therefore, different implementations of the exclude list for different platforms may be required. For example, presently the EMC NetWorker Block-Based Backup solution that is available for the Microsoft Windows platform is based on the VSS functionality provided by the Microsoft Windows OS (Operating System). An OS-independent technique for implementing the exclude list may be useful.